1. Background of the Invention
This invention relates to material conveyor systems and more particular to material conveyor systems that utilize free roaming mobile apparatus for application in a work area such as a factory and still more particular to material transportation systems that utilize television cameras as a means of tracking and guiding the free roaming mobile apparatus and still more particular to material transportation systems that uses a visual navigation system that has the capabilities of regenerating images that are obstructed from view of the sensors or television cameras which are necessary for guidance of the mobile apparatus.
In the application of remote control apparatuses to the manufacturing environment a preliminary requirement is the ability to obtain location and status information from the remote control apparatus. Sensors have been used in the past but with free roaming mobile apparatus the use of sensors becomes difficult because of their generally stationary specifications.
Visual systems that are currently being developed have a problem of guidance reference points being obstructed from view during the manufacturing operation.
2. Summary of the Invention
A manufacturing system has a material handling system that uses free roaming mobile apparatus that are under the control of a visual navigation system that has the capability of regenerating images that are temporarily obstructed from view of a visual navigation system that uses the images to provide commands that navigate an electrical controllable apparatus such as a mobile robot. The mobile robot is fitted with a minimum of three navigation beacons which emit a light visible to overhead television cameras. The beacons area arranged so as to form a triangle. The shape and the dimension of the triangular patterns are measured and stored in a memory unit within the visual navigation system. When a beacon is blocked from view of the television cameras the visual navigation will regenerate the coordinate of the the blocked beacon and provide the necessary navigation commands to the mobile robot.
The mobile apparatus includes a plurality of light sources or beacons arranged in a triangular pattern in the form of a right-handed asymmetrical triangle. Automatic regeneration of the blocked image is made by determining which two beacons are visible and their centroids are obtained. Two circles are circumscribed around each centroid and four possible location are obtained at the intersections of the four circles. A first primary candidate is obtained from two of the four possible locations by hitting the length of a chord that connects a first intersection to a first centroid the first intersection and the length of the chord that connects the second centroid to the first intersection. The hypotenuse is identified and the chords are ordered in a clockwise direction from the hypotenuse. The first primary candidate is the first intersection if the chords increase in length and the second intersection if the chords decrease in length.
The length of the chords that connect the first primary candidate to the third intersection and to the fourth intersection is used to select the secon primary candidate with the longer of the two being the second primary candidate. The obstructed beacon's location is identified as the primary candidate that is closes to a plumb line associated with the viewing television camera.
It is the object of this invention to provide a visual navigation system for a mobile robot that is impervious to interference caused by visual obstructions.
It is another object of the invention to provide a visual navigation system in which a mobile robot has three navigational beacons and the visual navigation systems can navigate the mobile apparatus even in the event of the obstruction or non-operation of one of the beacons.
These objects and advantages will become more apparent from the reading of the specification in conjunction with the figures in which: